Effect
on South American CL:
This proposal would add Poospiza whitii to the SACC list, by splitting it from Poospiza nigrorufa.

Background: Three subspecies are currently
recognized in this complex: nigrorufa,
whitii, and wagneri, the latter of which has been considered doubtfully
distinct from whitii. Both nigrorufa and whitii were historically treated as full species until Hellmayr
(1938) lumped them by treating whitii as
the western subspecies of P. nigrorufa. Thereafter, nigrorufa and whitii were treated as a single geographically variable species but
by some authors as full species; see Jordan et al. (2017) for details.

Genetic data indicate that nigrorufa and whitii are
well differentiated sister taxa with levels of mtDNA divergence (ca. 2.5% for
cyt-b and ND2) similar to those of other Poospizinae sister species (Shultz and
Burns 2013).

SACC proposal 79 failed to pass due to lack of detailed published
analyses, especially on vocal differences.

New
information: Jordan
et al. (2017) showed that nigrorufa
and whitii differ in 1) plumage
coloration and degree of dimorphism, 2) morphometric traits, 3) habitat,
distribution and ecological niche models, 4) vocal characters, and that 5) in
reciprocal playback experiments they ignore the other taxon while answering
strongly to their own vocalizations.

1) Plumage: In the slightly dimorphic nigrorufa, males have tawny rufous
throat, breast and flanks, and are brownish grey with slate tinged upperparts
(crown, neck, back and
rump), while females differ in the orange tinge of ventral parts and in the
more olivaceous upperparts. Sexes of nigrorufa
are hard to distinguish both in field and museum specimens. On the contrary, in
the markedly dimorphic whitii, males
have dark chestnut throat, breast and flanks, and slate upperparts, while
females exhibit tawny pale orange throat, breast
and flanks, and olivaceous light-brown upper parts (Fig. 1). In the field,
females of whitii exhibit paler
ventral colors, and more olivaceous upperparts than both sexes of nigrorufa. The key to correct
identification seems to be the extent of the white tip of the tail, which is
much greater in whitii than in any
sex of nigrorufa.

Jordan
et al. (2017) also proposed that the subspecies wagneri be treated as a synonym of whitii because they were unable to find any consistent plumage
differences.

2) Morphometrics: Specimens of nigrorufa had significantly higher and longer bill, longer tarsus
and wings, and were~10% heavier than whitii
(n=106 nigrorufa and n=91whitii). Both species were sexually
dimorphic, with males exhibiting longer wings and tails than females.
Within-sex comparisons between species show that nigrorufa has longer wings, but not longer tails, than whitii (Fig. 2).

4) Vocalizations: Songs (108 individuals; nigrorufa n= 81, whitii n= 27) and calls (18 individuals; nigrorufa n=14, whitii n=
4) differed dramatically (Fig. 4). The simple song of nigrorufa consists of one phrase with three pure whistled notes, that
is repeated a variable number of times. This phrase is usually transliterated
as pleased to meet you in English, quem te vestiu in Portuguese, or bichi-bichi in Spanish. The general
shape and order of the three notes of the song of nigrorufa are very consistent throughout
the range of the species.

The complex song of whitii is composed of a succession of a variable number of notes
whose quality and order varies greatly from individual to individual. In stark
contrast to nigrorufa, the number of
notes performed by each analyzed individual of whitii varied between 8 and 12. A complete song is a rhythmic
series of single melodious notes, among which paired melodious notes and a few
trills are irregularly interspersed that might be represented as choo we, tip-tip, sweet peer, tweak, trrree, sweet peer.

The numerous calls of both species are easily
distinguished with the aid of spectrograms, but are virtually impossible to
distinguish in the field (Fig 4.).

5) Reciprocal playback experiments: 20 reciprocal sandwich-playback
experiments were performed in Argentina during the breeding season. In all
experiments, the ten males of nigrorufa
and the ten males of whitii responded
aggressively to conspecific vocalizations by approaching to the sound source
and singing, while ignoring heterospecific ones, regardless of stimulus order
(n=15 conspecific and 15 heterospecific stimuli for each species).

Recommendation: We recommend a YES vote. All lines
of evidence clearly show that nigrorufa
and whitii belong to different
species under any species concept. This long overdue split is now fully
justified with solid integrative evidence, including behavioral responses to
mating cues.

Comments
from Stiles: "YES.
The combination of genetic, morphological and ecological data clearly shift the
burden of proof to those favoring conspecifity of whitii."

Comments from Zimmer: “YES.Multiple data sets confirm the
distinctiveness of these two taxa, and the playback experiments confirm the
importance of the vocal differences, which were noted by Ridgely and Tudor
(citing R. Straneck) as far back as 1989.”

Comments from Remsen: “YES.The playback trials in particular are
convincing evidence that these taxa have diverged to the point that free gene
flow no longer likely.”

Comments
from Claramunt:
“YES.
The evidence is solid, in my opinion.”

Comments from Cadena: “YES. The work by Jordan et al. is an an
excellent, integrative taxonomic study. I do not think that morphometric analyses
revealing differences in measures of central tendency are very useful for
species delimitation (especially for allopatric populations) and I think that
ecological differences as revealed by niche models are especially revealing in
cases unlike the present one where potential distributions suggest there is
potential for populations to come in geographic contact yet they remain
distinct (we described this with Andrés Cuervo in a paper in 2010 but the idea
has not gained much traction). Nonetheless, all the evidence points in the same
direction that there are two different species here.”